(WSJ) - $10.2 trillion is the amount of money advanced-nation governments will need to borrow in 2011. As the debts of advanced countries rise to levels not seen since the aftermath of World War II, it’s hard to know how much is too much. But it’s easy to see that the risk of serious financial trouble is growing.

Next year, fifteen major developed-country governments, including the U.S., Japan, the U.K., Spain and Greece, will have to raise some $10.2 trillion to repay maturing bonds and finance their budget deficits, according to estimates from the International Monetary Fund. That’s up 7% from this year, and equals 27% of their combined annual economic output.

Aside from Japan, which has a huge debt hangover from decades of anemic growth, the U.S. is the most extreme case. Next year, the U.S. government will have to find $4.2 trillion. That’s 27.8% of its annual economic output, up from 26.5% this year. By comparison, crisis-addled Greece needs $69 billion, or 23.8% of its annual GDP.

So far, with the notable exception of Greece, major advanced nations haven’t had too much trouble raising the money they need. Japan’s domestic investors have consistently bought its government bonds despite their low yield. Foreign investors have been snapping up U.S. Treasury bonds, which remain the world’s premier safe-haven investment.﻿